Comparative response of wheat and oilseed rape to nitrogen supply: absorption and utilisation efficiency of radiation and nitrogen during the reproductive stages determining yield

Autor: Rabbinge, R., Schapendonk, A. H. C. M., Slafer, G. A., Dreccer, M. F.
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Zdroj: Plant & Soil; 2000, Vol. 220 Issue 1/2, p189, 0p
Abstrakt: We investigated the response of spring wheat and oilseed rape to nitrogen (N) supply, focusing on the critical period for grain number definition and grain filling. Crops were grown in containers under a shelter and treated with five combinations of applied N. Wheat and oilseed rape produced comparable amounts of biomass and yield when corrected for the costs of biomass synthesis (SC). From the responses of biomass and yield to late N applications and the apparent contribution of mobilised biomass to yield, it seems that the yield of oilseed rape was more source-limited during grain filling than that of wheat, particularly at the medium and high N levels. Both species recovered equal amounts of N from the total available N in the soil and had similar N use efficiencies, expressed as yield per unit of N absorbed. However, oilseed rape had higher efficiency to convert absorbed N in biomass, but lower harvest index of N than wheat. Oilseed rape had similar or lower root biomass than wheat, depending on N level, but higherroot length per unit soil volume and specific root length. The specific uptake rate of N per unit root dry weight during the critical period for grain number determination was higher in oilseed rape than inwheat. In wheat, N limitation affected growth through a similar or lower reduction in radiation use efficiency corrected for synthesis costs (RUE_SC) than in the cumulative amount of intercepted photosynthetically active radiation (IPARc). In oilseed rape, lower growth due to N shortage was associated more with RUE_SC than IPARc, during flowering while during grain filling both components contributed similarlyto decreased growth. RUESC and the concentration of N in leaves and inflorescence (LIN%) decreased from flowering to maturity and were curvilinearly related. Oilseed rape tended to have higher RUESC than wheat at high N supply during the critical periodfor grain number determination, and generally lower during grain filling [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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